3.7 Ecosystems
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NATURAL HERITAGE 175 3.7 Ecosystems A variety of ecosystems can be found along the Ottawa River. Numerous provincial parks, conservation areas, ecological reserves, and Areas of Natural and Scientific Interest (ANSI) have been established along the river’s course. Twenty‐nine environmentally sensitive areas have been identified between Lac Dollard des Ormeaux and Lac la Cave on both the Ontario and Quebec shores (Haxton and Chubbuck 22). Each of these communities contains a fascinating array of species that interact in unique ways to produce a variety of distinct natural communities. Often, conservation groups and governmental organizations are working in tandem for the protection of these ecosystems. In many cases, these same groups provide excellent educational opportunities for the public through on‐site visits and guided tours. However, when ecosystems are highly sensitive, visitors must be cautious of making even seemingly small impacts on the natural environment. 3.7.1 Riverine Systems Figure 3.39 Along the Ottawa River Rivers shape neighbouring ecosystems by providing drinking water, microclimates, barriers to migration, and food. Dams and reservoirs along the Ottawa create significant changes to the river’s ecosystems. Dams have benefited Walleye along the river because they spawn in the resulting turbid waters. However, dams disrupt the migration and survival of other fish species, such as the River Redhorse. This fish is highly sensitive to siltation and pollution – siltation often occurs upstream of dams. The Northern Brook Lamprey, another species of concern, is Lavigne Francis : Source adversely affected by changes in the average water temperature due to lowering water levels, often a result of dam functioning (CWS: “Species at Risk”). The McLaurin Bay Project The McLaurin Bay project in Gatineau aims to ensure the protection and the enhancement of habitats with fauna of particular interest. It presently encompasses 520 hectares of wetland and riverine habitats, and is part of a larger project seeking to protect the north shore of the Ottawa River between Hull and Calumet, a stretch within which a great deal of the wetlands of the Ottawa River are found. The project is working to acquire privately owned lands in order to consolidate the properties presently belonging to the Quebec government. One desired outcome of this would be the creation of further wetlands in order to increase the biological productivity of the region. 3.7.2 Lacustrine (Lake) Systems The Ottawa River flows through numerous lakes, the largest of which are Grand Victoria, Simard, Temiskaming, Allumette, Chats, and Deschênes. Many of these lakes have been formed by dams NATURAL HERITAGE 176 that flooded immense forested areas. Flow regulation for hydroelectric production results in the conversion of lotic ecosystems to lentic ecosystems upstream of dams. In other words, water accumulates upstream of dams and floods the land, creating a lake in which water is relatively static and in which sediment accumulates with time. Downstream of the dam, water is generally in constant movement. Rare plant species can be found in various lakes along the Ottawa River, including Braun’s Quillwort, Bald Rush, Torrey’s Bald Rush, Water Crowfoot and four species in the potamogeton family (Potamogeton pusillus, Potamogeton perfoliatus, Potamogeton robbinsii and Potamogeton spirillus). Ontario has identified the Map Turtle as a species at risk. Increases in shoreline development, declines in habitat quality, and increases in human disturbances are probable culprits. Alternately, invasive Zebra Mussels may be responsible, as this species has reduced the population of the Map Turtle’s traditional prey (ROM: “Species at Risk”). 3.7.3 Wetlands Figure 3.40 Wetland Along the River Wetlands are the most productive and diversified ecosystems along the Ottawa River. They act as purifying sponges, filtering pollutants and excess nutrients. They also retain water, and then slowly replenish ground water sources as they diminish. Wetlands are vital to many microbes, plants, fish and wildlife, some rare or threatened, as these unique systems provide feeding and breeding grounds, habitat, migration halts, and shelter. There are five types of wetland: swamps, marshes, bogs, and fens. Each type is found at Source : Claude Beaudoin various points along the Ottawa River. Swamps Swamps are flooded areas that support ligneous (woody) species. Water levels are often high in the spring and then quite low in the summer. In springtime, swamps are true outdoor concert‐halls, as they are important reproduction sites for various species of frogs and salamanders. The Wood Street Swamp, a municipal park, protects one of the Ottawa River’s southern swamps. The Westmeath Provincial Park has a significant swamp that is alive with migrating ducks in spring and autumn. Stony Swamp Conservation Area Stony Swamp Conservation Area is located just south of the Ottawa River in the National Capital Greenbelt. The area comprises almost 2000 hectares of woodland, wetland and regenerating old field, and represents over 700 species of plant. Many interesting plant communities can be found here including a Sugar Maple forest, small alvar clearings, marsh wetlands and beaver ponds, and regenerating pastures. Stony Swamp Conservation Area also supports a large variety of wildlife, including Canada Geese and other waterfowl, Beaver, woodland birds and the Northern Flying Squirrel (NCC: “Stony Swamp”). NATURAL HERITAGE 177 Marshes Marshes are wetlands that are frequently or continuously inundated with standing or slow‐moving water (in the shallow water along the boundaries of lakes, ponds, and rivers). They are considered the most productive of all wetlands, and are characterized during the summer months by emergent soft‐stemmed vegetation that is adapted to saturated soil conditions. Several protected areas have been established to conserve the numerous marshes found along the Ottawa River. Muskellunge and Pike are known to spawn in the marshes of the Ottawa River. The Eastern Spiny Softshell Turtle is one of the rarest turtles in Canada, and is at risk both provincially and nationally. These turtles have been found along the Ottawa River in a variety of marshy habitats, including marshy creeks, marshy lagoons, ditches, and nearby ponds. Bogs Bogs are covered with a layer of floating vegetation that looks like solid ground, and are usually found in northern territories. Exceptions to this rule, the Alfred Bog and the Mer Bleue Bog are two boreal peat bogs along the Ottawa River. Both are situated near the Ottawa River, east of the city of Ottawa. A number of the plants and animals in these park areas are considered rare, either regionally, provincially or nationally. Drainage around the margins of the bogs threatens the health of these unique ecosystems. Alfred and Mer Bleue Bog Alfred Bog The Alfred Bog is a boreal peat bog hundreds of miles south of anything like it. At 4,200 hectares (10,000 acres), it is the largest bog of its kind in southern Ontario, large enough to give refuge to many plants and animals that were stranded as the warming climate caused the boreal forest to retreat northward with the end of the last Ice Age. This peat bog has been accumulating for 10,000 years, and shelters many plants and animals that are rare or endangered, some of which are of national significance. Examples include the Bog Elfin Butterfly, Fletcherʹs Dragonfly, Spotted Turtle, White Fringed Orchid, Atlantic Sedge and Rhodora. In fact, the bog has been designated by the Ontario Ministry of Natural Resources as a ʺClass 1 Wetlandʺ and an ʺArea of Natural and Scientific Interest (ANSI)ʺ. Being a domed peat bog, the Alfred Bog is unlike the kettle bogs most commonly encountered south of the Hudson’s Bay lowlands. Domed bogs, unlike kettle bogs, drain in all directions from the dome and only receive nutrients from rain and snow. The dominant vegetation in both types of bog is Sphagnum Moss, known to gardeners as peat moss. Sphagnum Moss thrives in the interior of bogs where cool, wet, oxygen starved, nutrient poor, acidic conditions prevail. The dome is formed over millennia as sphagnum moss gradually wicks up water from below. Alfred Bog lies in the east end of an abandoned channel of the Ottawa River. This was once the main channel of a great river flowing down the Ottawa Valley and into the Atlantic Ocean, draining a glacial lake centred in Manitoba. Because of reduced flow and glacial rebounding, the river abandoned its old channel and moved to its present location. NATURAL HERITAGE 178 The most significant impact upon Alfred Bog Figure 3.41 Aerial View of the Alfred Bog over the years has been the conversion of bog land for agricultural purposes. The first settlers in the area found the bog to be of little use for farming and an obstacle to building roads. Nevertheless, over the years, drainage around the margins has reduced it to about a third of its original size (Pope: “Alfred Bog”). Mer Bleue Bog The Mer Bleue Bog is Alfred Bog’s “smaller twin.” It is designated as an Ontario Provincial Source : Ottawa River Legacy Landmark Network Conservation Area, and is situated in the eastern portion of the National Capital Region less than 10 kilometres from Ottawa. Like Alfred Bog, it is of great ecological value as an example of a northern ecosystem, justifying its designation as an Internationally Significant Wetland under the United Nationsʹ Ramsar Convention (NCC: “Mer Bleue Bog”). Approximately 50% of Mer Bleue is a raised boreal peat dome, or Sphagnum bog, a system typically occurring in the boreal forests of northern Canada. The bog’s hydrological features are unusual, with saline groundwater sources as well as peat deposits of up to six metres thick. Much of the border of the bog has been transformed by beaver dams into ponds and marshlands. Underlying clay deposits further reduce drainage, such that water levels remain at or near the surface of the bog for most of the year (Ramsar: “Canada”).